Participant Support Travel Scope-CAREER: Influence of Soil Phosphorus on Soil Organic Matter Dynamics

In natural ecosystems, the primary source of phosphorus (P) is bedrock. In soils, weathering of bedrock and the formation of secondary soil minerals controls the speciation and retention of P. The same processes that control soil P dynamics are also important in the formation of soil organic matter (SOM), which relies on complex interactions among soil minerals, plant litter quality, and microbial activity. Soil organic matter is a major reservoir of macro- and micronutrients and provides benefits for soil fertility and soil health. As such, SOM sequesters large quantities of P. But, the role of P in SOM formation and stability is poorly understood, which limits our knowledge of both the soil P and C cycles. The overall objective of the proposed work is to elucidate the specific role of P in SOM stabilization. The proposed research will address these specific aims: (i) To describe the mechanisms by which organic and inorganic P control mineral associated organic matter (MAOM) adsorption and stabilization; (ii) To determine the P forms that exist in and relate to SOM in P-rich and P-limited ecosystems; and (iii) To quantify organic and inorganic P control of MAOM dynamics within P-rich and P-limited ecosystems. Upon completion of the proposed aims, the impact of P on SOM persistence and stability will be known. The proposed research site is in Kentucky (KY), which is an ideal testbed because it contains large regions of carbonate and other sedimentary lithologies that vary by their P content. To accomplish these aims, a novel combination of physical and chemical P and SOM fractionations, isotopic proxies, and mass spectrometric techniques will be used to quantify and characterize SOM dynamics and their interactions with soil P dynamics.